Fiber optic probe having fibers with endfaces formed for improved coupling efficiency and method using same

A fiber optic probe, said probe having a longitudinal axis, said probe comprising:

• at least one transmitting fiber having a first optic axis and a first endface, said first endface formed so that light passing through said first endface passes through said first endface at an angle less than perpendicular with respect to said first endface, said transmitting fiber oriented so that light passing through said first endface is directed toward said longitudinal axis;
• at least one receiving fiber having a second optic axis and a second endface, said second endface formed so that light passing through said second endface passes through said second endface at an angle less than perpendicular with respect to said second endface, said receiving fiber oriented so that light passing through said second endface is directed toward said longitudinal axis;
• and
• means for holding said transmitting and receiving fibers in spaced relation so that said first and second optic axes are parallel with respect to one another, said holding means holding said transmitting and receiving fibers so that when a light scattering means is positioned within a range beyond said first and second endfaces, a portion of light transmitted from said transmitting fiber is reflected by said light scattering means and substantially collected by said receiving fiber, said holding means having an epoxy positioned between and adhering to said transmitting and receiving fibers, said epoxy containing a light absorber to minimize crosstalk between said transmitting and receiving fibers.

A method for increasing the light coupling efficiency of a fiber optic probe, said probe having a distal end and a longitudinal axis, said method comprising the steps of:

• forming a first endface on a first fiber so that light passing through said first endface passes through said first endface at an angle less than perpendicular with respect to said first endface, said first fiber carried in said distal end of said probe, said first fiber having a first optic axis;
• forming a second endface on a second fiber so that light passing through said second endface passes through said second endface at an angle less than perpendicular with respect to said second endface, said second fiber carried in said distal end of said probe, said second fiber having a second optic axis;
• aligning said first and second fibers so that first and second optic axes are parallel;
• axially orienting said first and second fibers so that when a light scattering means is positioned within a range beyond said first and second endfaces, a portion of light transmitted by one of said first and second fibers is reflected by said light scattering means and substantially collected by the other of said first and second fibers;
• and
• inserting an epoxy in said distal end of said probe, said epoxy adhering to said first fiber, said second fiber and said distal end so that said first and second fibers are held in said distal end, said epoxy containing a light absorber to minimize crosstalk between said first and second fibers.